(1) Field of the Invention
The present patent application relates to water-soluble, encapsulated peroxycarboxylic acid particles, processes for their manufacture, and their use, particularly in liquid detergents or cleansing agents.
In liquid detergents and cleansing agents, particularly when they are in liquid form and/or comprise large amounts of water, there may result a decrease in their activity and thereby a decrease in the overall washing performance of the composition because of interactions between the individual ingredients due to chemical incompatibility, even when the composition is stored for a relatively short time. In principle, this decrease in activity concerns all detergent ingredients that in the washing process undergo chemical reactions that contribute to the washing performance, particularly bleaching agents and enzymes, although tensidic or chelating ingredients that are responsible for dissolution processes or complexation steps, are not completely storage stable in liquid, particularly aqueous systems, particularly in the presence of the cited chemically reactive ingredients.
On various occasions, it has been proposed to solve this problem by not simultaneously incorporating all ingredients required for a good washing or cleaning result into a liquid composition, but rather by supplying the consumer with several components that have to be mixed together shortly before, or during the washing or cleaning process and which each only comprise ingredients that are compatible with each other and first come into contact together during the course of the application. The combined dosing of several components, in comparison with dosing only a single composition, is often felt by the consumer as being too laborious.
Imidoperoxycarboxylic acids are known bleach ingredients in detergents and cleansing agents. However, their poor storage stability is problematic, especially in liquid formulations and at higher pH values. Proposals have already been made in the prior art to solve this problem.
(2) Description of Related Art, Including Information Disclosed Under 37 C.F.R. §§1.97 and 1.98.11.
In European Patent Application EP 0 510 761 A1, particles of 6-phthalimidoperoxyhexanoic acid are described, which are encapsulated with a layer of wax with a melting point in the range 40° C. to 50° C. The bleaching agent can therefore only be released from these particles at temperatures above the melting point of the wax.
European patent application EP 0 653 485 discloses capsule compositions, in the interior of which, 6-phthalimidoperoxyhexanoic acid is present as a dispersion in oil. The manufacture of these capsules therefore requires a prior emulsification process to manufacture the peracid dispersion.
The result of the measures described in the prior art for stabilizing bleaching agents, particularly in liquid compositions, is not always sufficient. For long storage times, the bleaching agent has been observed to decompose—in spite of the presence of the cited stabilizers—with a consequent loss in bleach activity and thus in washing power.